JP2005169405A - Laser beam machining apparatus, cooling device for laser beam machining apparatus, and method for cooling processed lens of laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel laser beam machining apparatus which effectively uses a purge gas or an assist gas to cool a processed lens although such a gas is originally used for other purposes, and which is equipped with a means of eliminating an outside influence which the purge gas or assist gas passing through gas passages may be subjected. <P>SOLUTION: In the laser beam machining apparatus, a laser beam emitted from a laser beam source is narrowed down by the processed lens 32 and is irradiated to a workpiece from the tip of a nozzle 31. A device 1 for cooling the purge gas P or the assist gas is installed in the passages 21 and 22 of the purge gas P or the assist gas blown onto the processed lens 32. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus, a cooling apparatus used in the laser processing apparatus, and a processing lens cooling method of the laser processing apparatus.

  The laser processing apparatus squeezes the laser beam sent from the laser light source with a processing lens (or a condensing lens) provided in the final stage and irradiates the workpiece. This processed lens is heated by a laser passing therethrough, and the focal length may change due to thermal expansion (thermal lens action or thermal lens effect). Therefore, in order to reduce or suppress the action of the thermal lens and keep the focal length of the processed lens constant, it is only necessary to suppress or prevent heating of the processed lens, or to cool the processed lens by turning it over. Thus, a technique (air cooling) for cooling a processing lens using a purge gas or an assist gas used in a laser processing apparatus has been proposed. The reason for using air cooling technology is to prevent the risk of water leakage, and since water cooling is not so different from air cooling because of indirect cooling, it is most convenient and simple to use purge gas or assist gas for air cooling. It is rational (see Patent Document 2).

  Patent Document 1 discloses a configuration in which an assist gas passage is provided in a holder surrounding a processing lens receiver, and the assist gas is guided to the processing lens and then guided to the nozzle. Patent document 2 is disclosing the structure which provides the blower outlet which blows off gas from the edge part of a process lens. Patent Document 3 discloses a configuration in which an assist gas outlet is provided on the outer periphery of the processing lens. Patent Document 4 discloses a configuration in which a gas outlet for blowing gas at an oblique angle is provided on the surface of the laser light extraction window toward the substantial center of the heat generating portion of the laser light extraction window. In addition, in combination with air cooling with assist gas, for example, a cooling lens and cooling gas are used together to cool the processing lens (Patent Document 5), a cooling air blowing means for directly spraying the processing lens, and an upper part of the condenser lens. A configuration (Patent Document 6) is also provided in which an air blowing means for forming an air screen is provided.

JP-A-63-034590 (1 page, FIGS. 1 to 3) JP 05-077081 (pages 3 to 4, FIGS. 3 to 4) Japanese Patent Laid-Open No. 05-185265 (pages 2 to 4, FIGS. 1 to 5) Japanese Patent Application Laid-Open No. 09-174274 (pages 2 to 10, FIG. 1) JP-A-62-224489 (pages 2 to 3, FIG. 1) Japanese Patent Application Laid-Open No. 09-271974 (pages 2 to 3, FIGS. 1 to 4)

  Laser processing equipment lenses that are not suitable for water cooling can be air-cooled by bypassing the purge gas for removing dust originally attached to the processing lens and the assist gas that is blown to the processing part of the workpiece and blowing it to the processing lens. It seems the easiest and appropriate. The purge gas or assist gas serving as a cooling means for the processing lens is guided to the processing lens through a gas flow path from a supply facility (for example, a gas cylinder) provided separately from the laser processing apparatus.

  The gas flow path is generally a metal pipe, and is likely to cause an external influence, mainly heat exchange of the purge gas or the assist gas due to an increase in temperature, that is, an increase in temperature. For this reason, the metal pipe that normally forms the gas flow path is covered with a heat insulating material, but the temperature of the purge gas or the assist gas still increases. In particular, in a laser processing apparatus using a high-power laser that has begun to spread in recent years, it is difficult to supply a purge gas or an assist gas that maintains a sufficiently low temperature for cooling the processing lens. The processed lens could not be cooled by air cooling, and as a result, the generation of the thermal lens action could not be suppressed or prevented.

  Accordingly, a purge gas or an assist gas that is originally used for another purpose is more actively used for cooling the processing lens, and means for removing the influence of the external environment that the purge gas or the assist gas that passes through the gas flow path receives. In order to develop a new laser processing device provided, a cooling device attached to an existing laser processing device, and a cooling method applicable to the both, studies were conducted.

  What was developed as a result of the study is a laser processing device that squeezes the laser beam from the laser light source with the processing lens and irradiates the workpiece from the tip of the nozzle. A laser processing apparatus provided with cooling means for the purge gas or assist gas. The laser processing apparatus of the present invention corrects the influence of the outside world (increase in temperature) by the cooling means so that purge gas or assist gas having a temperature suitable for cooling the processing lens can be supplied. The target temperature of the purge gas or assist gas to be cooled is 15 ° C. to 35 ° C., preferably 20 ° C. to 30 ° C.

  Here, the cooling means includes (1) a configuration for simply cooling the purge gas or assist gas (relative cooling) and (2) a configuration for cooling the purge gas or assist gas toward the target temperature (absolute cooling). is there. The structure of relative cooling is a simple cooling means because the temperature of the purged purge gas or the assist gas varies when the rise in the temperature varies, but the temperature control of the purge gas or the assist gas is not required. On the other hand, absolute cooling not only increases the temperature of the purge gas or assist gas due to the influence of the outside world, but also prevents a temperature decrease in some cases, so that the purge gas or assist gas that is always at a constant target temperature can be supplied. To do. For this reason, the absolute cooling configuration requires a control unit that feeds back the temperature of the purge gas or the assist gas cooled by the cooling means to adjust the cooling action of the cooling means.

  Specifically, the cooling means includes a heat exchanging section that encloses a part of the gas flow path, and a medium circulating means that allows a heat exchange medium having a temperature lower than the purge gas or assist gas to flow into and out of the heat exchanging section. Cooling is performed by heat exchange between the gas and the heat exchange medium. The heat exchanging part is made of a metal block having a hollow inside, a box made of a metal plate, or the like, and a gap between the hollow part or the gas flow path and the metal plate becomes a medium flow path. When the heat exchange part is configured with a metal block, the gas flow path and the medium flow path can be separately provided, and only by interposing the heat exchange part made of the metal block in the existing gas flow path, There is an advantage that a gas flow path to which a cooling means is attached can be configured.

  When the heat exchanging portion wraps the meandering gas flow path integrally, the time for heat exchange with the purge gas or the assist gas is increased, and the cooling action is enhanced. In addition, as described above, the target temperature of the purge gas or assist gas to be cooled is not so low as 15 ° C. to 35 ° C., so the cooling medium is easy to obtain, easy to handle, and dangerous even if leaked. It is recommended to use cooling water without any water. The cooling water only needs to be at a lower temperature than the purge gas or the assist gas. For example, even in the case of the absolute cooling configuration, the purge gas or the assist gas can be sufficiently cooled to the target temperature by increasing the heat exchange time.

  When the present invention is used in an existing laser processing apparatus, a cooling apparatus attached to a laser processing apparatus that squeezes a laser beam sent from a laser light source with a processing lens and irradiates a workpiece from the tip of a nozzle, and is provided with a laser processing apparatus. A heat exchanging portion that wraps a part of a gas flow path of the purge gas or assist gas sprayed to the processing lens of the apparatus, and a medium circulating means for flowing in and out a heat exchanging medium having a temperature lower than the purge gas or assist gas into the heat exchanging portion. A cooling device used for a laser processing apparatus is used. As described above, the heat exchanging portion made of a metal block can be easily provided over the gas flow path in the existing laser processing apparatus.

  Also in this cooling device, it is preferable that the heat exchanging portion wraps the meandering gas flow path integrally. In this case, a part of the gas flow path in the existing laser processing apparatus is excised, and a separate gas flow path constituting the meandering gas flow path is interposed, and this meandering part is wrapped in a box which is a heat exchange part. Good. In the case of using a heat exchanging portion made of a metal block, a meandering gas flow path can be integrally provided in the metal block, so that there is an advantage that a meandering gas flow path need not be prepared separately. Further, the medium circulation means may flow cooling water having a temperature lower than the purge gas or assist gas flowing through the gas flow path into and out of the heat exchange unit.

  The present invention provides the processing lens of the laser processing apparatus that squeezes the laser beam sent from the laser light source with the processing lens and irradiates the work from the tip of the nozzle even when not using the laser processing apparatus or the cooling device provided in the laser apparatus. When the processing lens is cooled by spraying the purge gas or the assist gas, it is sufficient that the purge gas or the assist gas can be cooled to 15 ° C. to 35 ° C. by a cooling means provided in the gas flow path of the purge gas or the assist gas. For example, even if a cooling element or the like for directly cooling a metal pipe constituting the gas flow path is mounted, the present invention is applicable.

  The present invention provides a technique for more actively using the purge gas or assist gas originally used for another purpose for cooling the processing lens, thereby suppressing the occurrence of the thermal lens action of the processing lens even in the hot summer season. There is an effect that can be prevented. In the laser processing apparatus to which the present invention is applied, a cooling means is provided in a gas flow path as close as possible to the processing lens, and the processing lens can be cooled before the temperature of the cooled purge gas or assist gas rises again.

  Further, the cooling device of the present invention can be used for an existing laser processing apparatus. In this case, it is difficult to attach the cooling device to a free position of the gas flow path as compared with the case where the present invention is applied to a new laser processing apparatus, but a purge gas or an assist gas that reliably provides a cooling action compared to the conventional case is used. The effect that can be supplied toward the processing lens can be enjoyed in the same manner as the newly-installed laser processing apparatus.

  Even when the cooling device cannot be used, if the purge gas or the assist gas can be separately cooled to a target temperature of 15 ° C. to 35 ° C., preferably 20 to 30 ° C., the generation of the thermal lens action is suppressed or prevented. be able to. In addition, in any case, the absolute cooling configuration complicates the apparatus configuration for controlling the temperature of the purge gas or assist gas to be cooled. In the case of the configuration, the temperature control is not necessary, and the device configuration can be made relatively inexpensively. From this, it can be said that the present invention is a cost-effective technique in view of the effect of suppressing or preventing the occurrence of the thermal lens action obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially extracted configuration diagram of a laser processing apparatus in which a cooling apparatus 1 according to the present invention is interposed in the middle of an existing gas flow path 21, 22, FIG. 2 is an exploded perspective view of the cooling apparatus 1, and FIG. FIG. 4 is a plan view of the cooling device 1, FIG. 5 is a cross-sectional view taken along line AA in FIG. 3, FIG. 6 is a cross-sectional view taken along line BB in FIG. FIG. 8 is a perspective view showing a cross section corresponding to DD in FIG. 4, and FIG. 9 is a perspective view showing a cross section corresponding to EE in FIG. In this example, the cooling water W is used as a heat exchange medium, and the purge gas P sprayed on the upper surface of the processing lens 32 installed in the nozzle 31 of the laser processing apparatus is cooled. The assist gas A can be configured in the same manner and can be used in combination with the configuration of the purge gas P, but this time, it will be represented by an example of the purge gas P, and illustration and description thereof will be omitted.

  As shown in FIG. 1, the cooling device 1 of the present invention, for example, separates the pipes constituting the gas flow path of an existing laser processing apparatus into an upstream existing gas flow path and a downstream existing gas flow path 22. It comprises a heat exchange section 11 to be interposed, an upstream medium external flow path 23 and a downstream medium external flow path 24 through which cold water W as a heat exchange medium flows in and out of the heat exchange section 11. In this example, the upstream existing gas flow path 21 and the downstream existing gas flow path 22 are directly connected to the meandering gas flow path 12 in the heat exchange section, but the heat exchange section 11 of the laser processing apparatus Depending on the installation position, an intermediate gas flow path connecting the upstream existing gas flow path 21 and the downstream existing gas flow path 22 and the heat exchanging section 11 may be used.

  As shown in FIGS. 2 to 9, the heat exchanging portion 11 of this example includes a main body 111 formed of a metal block having a meandering gas flow path 12 and a medium flow path 13 provided separately therein, and the main body 111. Metal side plates 112 and 113 that block the meandering gas flow path 12 and the medium flow path 13 that are open on both side surfaces. The metal side plates 112 and 113 are members that seal the meandering gas flow path 12 and the medium flow path 13 except for the gas inlet 121 and the gas outlet 122, and the medium inlet 131 and the medium outlet 132. It is desirable that it can be firmly fixed to. For this reason, the metal side plates 112 and 113 of this example are fastened to the main body 111 with bolts 114 at the four corners. In addition, the metal side plates 112 and 113 may be fixed to the main body through a sealing sheet obtained by cutting out the opening shapes of the gas flow path 12 and the medium flow path 13 that are opened on the side surface of the main body 111.

  The meandering gas flow path 12 is composed of a multi-stage straight flow path 123 penetrating over both side surfaces of the main body 111, and a folded recess 124 provided in the left and right staggered upper and lower straight flow path ends 123. The metal side plates 112, 113 close the folding recess 124, whereby the multistage linear passages 123 are connected to each other through the folding recess 124, thereby forming the meandering gas flow path 12. The gas inlet 121 of the meandering gas flow path 12 is opened to the upper stage of the metal side plate 112 on the left side at a position where the uppermost straight passage 123 communicates, and connects the upstream existing gas flow path 21. Further, the gas outlet 122 of the meandering gas flow path 12 opens to the lower stage of the metal side plate 113 on the right side at the position where the lowermost straight passage 123 communicates, and connects the existing gas flow path 22 on the downstream side. .

  Thus, the purge gas P flows from the upper straight flow path 123 to the lower straight flow path 123. This has the meaning of ensuring a smooth flow of the purge gas P without resisting gravity. For example, if there is a sufficient pressure of the purge gas P, it will flow from the lower straight flow path 123 to the upper straight flow path 123. It may be. In addition, the meandering gas channel may be configured in a horizontal plane so that each straight channel is equally affected by gravity. This meandering gas channel 12 has a longer channel length than the size of the heat exchanging portion 11, increases the range of heat exchange with the main body 111 or the cooling water W described later, and efficiently cools the purge gas P. Has an urging effect.

  The medium flow path 13 penetrates between the pair of main heat exchange spaces 133, 133 arranged across the gas flow path 12 of the main body 111 and the straight flow paths 123 of the meandering gas flow path 12, and both the main heat exchange spaces 133, 133 are formed. And a connection channel 134 for connecting the two. The medium inlet 131 of the medium flow path 13 is open to the upper stage of the metal side plate 113 on the right side surface at a position communicating with the upper portion of one main heat exchange space 133, and connects the upstream medium external flow path 23. To do. Further, the medium outlet 132 of the medium flow path 13 is opened to the lower stage of the left side metal side plate 112 at a position communicating with the lower part of the other main heat exchange space 133, and the downstream medium external flow path 24 is opened. Are connected.

  The cooling of the purge gas P by the heat exchange unit 11 of this example is as follows. The cooling water W that has flowed into the one main heat exchange space 133 from the medium inlet 131 flows into the remaining main heat exchange space 133 through the connection flow path 134 and flows out from the medium outlet 132. Each main heat exchange space 133 is a substantially rectangular space in front view that is slightly smaller than the front shape or the back shape of the main body 111. The cooling water W filling the main heat exchange space 133 first increases the temperature of the entire main body 111. Therefore, heat exchange is performed between the main body 111 and the purge gas P. And, directly, the part where each main heat exchange space 133 and the straight flow path 123 are closest to each other, and the part where the connection flow path 134 and the straight flow path 123 passing through between each straight passage 123 are closest Thus, heat exchange is performed between the cooling water W and the purge gas P.

  Here, the heat exchange between the main body 111 and the purge gas P and the heat exchange between the cooling water W and the purge gas P are movement of thermal energy from a relatively high temperature side to a low side. The present invention aims to cool the purge gas or assist gas supplied toward the processing lens, and assumes that the purge gas or assist gas has risen in temperature. From this, in the case of this example, the heat exchange appears as a transfer of thermal energy from the purge gas P to the main body 111 or the cooling water W, and the purge gas P is cooled. For example, in summer and the like, the purge gas P is heated by the high outside air temperature in the process of flowing from the cylinder to the existing upstream gas passage 21, and becomes 30 ° C. or higher. Here, if the temperature of the cooling water W is 20 ° C. and the volume of the medium flow path 13 is larger than the volume of the meandering gas flow path 12 in the heat exchanging section 11, the temperature of the purge gas P approaches the temperature of the cooling water, 30 It becomes below ℃.

  Since the cooling water W is continuously supplied from the medium inflow port 131, it is possible to always receive the thermal energy from the purge gas P. Further, since the cooling water W that has received the thermal energy from the purge gas P is continuously discharged from the medium outlet 132, the thermal energy is also sequentially discharged from the heat exchange unit 11. On the other hand, heat energy transferred to the main body 111 and heat energy transferred from the cooling water W to the main body 111 are released from the outer surface of the main body 111. For this reason, for example, if heat radiation fins are provided on the outer surface of the main body to increase the surface area, heat energy can be efficiently released.

  On the contrary, when the temperature of the purge gas P is lower than the temperature of the main body 111 or the cooling water W, the purge gas P receives heat energy from the main body 111 or the cooling water W and is heated (in this case, the “cooling water W”). Is not appropriate, but it is used because of the consistency of terminology). That is, the heat exchanging unit 11 moves thermal energy so as to achieve thermal equilibrium between the main body 111 or the cooling water W and the purge gas P. As an application of the present invention, a target temperature of the purge gas P (15 ° C. to 35 ° C., preferably 20 ° C. to 30 ° C.) is set, and a heat exchange medium is poured into the heat exchange unit 11 so as to reach the target temperature. As a result, the temperature of the purge gas P passing through the heat exchanging section 11 can be kept constant at the target temperature. As described above, the present invention is mainly aimed at cooling the purge gas or the assist gas, but has an effect of providing means for realizing the temperature management of the purge gas or the assist gas.

It is a partial excerpt block diagram of the laser processing apparatus which interposed the cooling device based on this invention in the middle of the existing gas flow path. It is a disassembled perspective view of the cooling device. It is a front view of the cooling device. It is a top view of the cooling device. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is CC sectional drawing in FIG. It is a perspective view showing the DD equivalent cross section in FIG. It is a perspective view showing the EE equivalent cross section in FIG.

Explanation of symbols

1 Cooling device
11 Heat exchanger
12 Meander gas flow path
13 Media flow path
21 Upstream existing gas flow path
22 Existing gas flow path downstream
23 Upstream media external flow path
24 Downstream media external flow path
32 Processing lens

Claims (8)

In a laser processing apparatus that squeezes a laser beam from a laser light source with a processing lens and irradiates a workpiece from the tip of a nozzle, the purge gas or assist gas is cooled in a purge gas or assist gas gas flow path sprayed onto the processing lens. A laser processing apparatus comprising means. The cooling means includes a heat exchanging portion that wraps a part of the gas flow path, and a medium circulating means that allows a heat exchange medium having a temperature lower than the purge gas or the assist gas to flow into and out of the heat exchanging portion. The laser processing apparatus according to claim 1, wherein cooling is performed by heat exchange with a heat exchange medium. The cooling means includes a heat exchanging unit that integrally wraps the meandering gas flow path, and a medium circulating unit that allows a heat exchange medium having a temperature lower than the purge gas or the assist gas to flow into and out of the heat exchanging unit. The laser processing apparatus according to claim 1, wherein cooling is performed by heat exchange with a heat exchange medium. The cooling means includes a heat exchanging portion that wraps a part of the gas flow path, and a medium circulation means that allows cooling water having a temperature lower than the purge gas or the assist gas to flow into and out of the heat exchanging portion. The laser processing apparatus according to claim 1, wherein cooling is performed by heat exchange with water. A cooling device attached to a laser processing device that squeezes a laser beam sent from a laser light source with a processing lens and irradiates a workpiece from the tip of a nozzle, and is a purge gas or an assist gas gas sprayed onto the processing lens of the laser processing device A cooling device used in a laser processing apparatus comprising: a heat exchanging portion that encloses a part of a flow path; and a medium circulating means that causes a heat exchanging medium having a temperature lower than purge gas or assist gas to flow into and out of the heat exchanging portion. The cooling device used in the laser processing apparatus according to claim 5, wherein the heat exchange unit integrally wraps the meandering gas flow path. 6. The cooling apparatus used in a laser processing apparatus according to claim 5, wherein the medium circulation means causes cooling water having a temperature lower than purge gas or assist gas flowing through the gas flow path to flow into and out of the heat exchange unit. When cooling the processing lens by blowing the purge gas or the assist gas onto the processing lens of the laser processing apparatus that squeezes the laser beam from the laser light source with the processing lens and irradiates the workpiece from the tip of the nozzle, the purge gas or the assist gas A processing lens cooling method of a laser processing apparatus, wherein the purge gas or the assist gas is cooled to 15 ° C. to 35 ° C. by a cooling means provided in a gas flow path.

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